1 4 8 D O C U M E N T 1 6 0 A P R I L 1 9 2 2 Do not forget my address if you come to Switzerland, either. I would very much enjoy seeing you again. Believe me to be, dear A. Einstein, your affectionate and devoted admirer, Romain Rolland. 159. From Paul Colin Brussels, 22 April 1922 [Not selected for translation.] 160. From Paul Ehrenfest [Leyden,] 22 April 1922 Dear Einstein, That’s fine!! Your postcard arrived today.[1] —I immediately sent you a telegram: Come. 29 April academy.: i.e., come if possible so that you can attend the academy meeting on April 29th.—Your presence could perhaps be of benefit to W. J. de Haas (confidentially!)[2] —The business with St. John[3] isn’t certain enough to take upon oneself the risk of a “prolonged Einstein”—No: better one Einstein today than a dozen Einsteins “day after tomorrow.” I would be very pleased if Brillouin came[4] —the only difficulty is that I cannot host him now. (You, anytime—because you can be bedded and boarded in any sta- ble.) As soon as you’re here I’ll write him immediately. Please write me right away when you are arriving where.—For us, and very spe- cially for the children, it is a great pleasure to be able to fetch you! You would have known from the Indian whooping that the children let out when I read out your postcard how deeply happy all of us are that you are coming. You are going to encounter here—at least for one whole evening (but perhaps also at the academy) the British physical chemist McDonnan.[5] He will be present- ing a talk each in Utrecht, Amsterdam, Leyden, and Groningen. If Sommerfeld’s IIIrd edition has already appeared, please bring it along.[6] After the academy meeting in Amsterdam you’d also be seeing Hertz, Fokker, W. J. de Haas, Holst,[7] and many other physicists.– You would have to depart from Leyden on the 29th at 1000 in the morning for Amsterdam in order to come to the academy.